ALBERT

Description: 〈p〉Mars is dry today, but numerous precipitation-fed paleo-rivers are found across the planet’s surface. These rivers’ existence is a challenge to models of planetary climate evolution. We report results indicating that, for a given catchment area, rivers on Mars were wider than rivers on Earth today. We use the scale (width and wavelength) of Mars paleo-rivers as a proxy for past runoff production. Using multiple methods, we infer that intense runoff production of 〉(3–20) kg/m〈sup〉2〈/sup〉 per day persisted until 1 Ga. Our improved history of Mars’ river runoff places new constraints on the unknown mechanism that caused wet climates on Mars.〈/p〉

Description: Geological observations that constrain the history of mantle convection are sparse despite its importance in determining vertical and horizontal plate motions, plate rheology, and magmatism. We use a suite of geological and geophysical observations from the northern North Sea to constrain evolution of the incipient Paleocene-Eocene Icelandic plume. Well data and a three-dimensional seismic survey are used to reconstruct a 58–55 Ma landscape now buried ∼1.5 km beneath the seabed in the Bressay region. Geochemical analyses of cuttings from wells that intersect the landscape indicate the presence of angiosperm debris. These observations, combined with presence of coarse clastic material, interpreted beach ridges, and a large dendritic drainage network, indicate that this landscape formed subaerially. Longitudinal profiles of palaeo-rivers were extracted and inverted for an uplift rate history, indicating three distinct phases of uplift and total cumulative uplift of ∼350 m. Dinoflagellate cysts in the surrounding marine stratigraphy indicate that this terrestrial landscape formed in 〈3 Ma and was rapidly drowned. This uplift history is similar to that of a slightly older buried landscape in the Faeroe-Shetland basin ∼400 km to the west. These records of vertical motion are consistent with pulses of anomalously hot asthenosphere spreading out from the incipient Icelandic plume. Using simple isostatic calculations we estimate that the maximum thermal anomaly beneath Bressay was 50–100°C. Our observations suggest that a thermal anomaly departed the Icelandic plume around 57.4 ±2.2 Ma at the latest, and travelled with a velocity 〉∼150 km/Ma. This article is protected by copyright. All rights reserved.

Description: The current global dataset of drainage system shapes has a relatively low spatial resolution. We obtained a new dataset (Basin90m) by calculating the drainage basins larger than 50 km2 globally using a 90-meter resolution Digital Elevation Model (DEM). The total number of drainage basins is 667629. For each drainage basin, we extracted the spatial distribution of the longest river channel and the sinuosity of the river. We computed fundamental geometric parameters for the drainage basins, such as area, length, width, aspect ratio, slope, and elevation. Basin90m consists of vector files (ESRI Shapefile format) containing global drainage basins and river channels. The file sizes for the basin and river data are 7.8 and 2.5 GB, respectively. All calculations were automated using a MATLAB script. For a more detailed description of Basin90m, please refer to our submitted data description article titled "A global dataset of the shape of drainage systems". The Basin90m dataset includes data in four sections. The first section comprises drainage basins globally with an area larger than 50 km². The data format is ESRI Shapefile. Eight morphometric indi-ces of the drainage system are stored in the attribute table of the basin shapefile. The "Basins" folder contains six subfolders, each representing a continent. Each continent's subfolder contains all the basins in that continent, categorized by different stream orders. For instance, the "South America" subfolder contains nine shapefile files corresponding to stream orders 1-9. The names of the shapefile files include their continent and stream order information. For example, "South_America_Basin_8.shp" represents all basins in South America with a stream order of 8. The second part of the Basin90m data consists of global main river channels. The longest river channel of each basin is stored in a folder named "Rivers". The internal structure of this folder is the same as the "Basins" folder. For instance, "South_America_River_8.shp" represents the main river channels in South America with a stream order of 8. The third part of Basin90m data is an Excel file named "Basin90m". This file contains eight morphometric parameters for all the basins. It includes both a globally merged sheet and sheets distinguishing different stream orders. The fourth part of Ba-sin90m data is a folder named "Matlab_code", which contains Matlab code for the automated ex-traction of drainage systems and their morphometric parameters.

Description: Drainage basins delineate Earth's land surface into individual water collection units. Basin shape and river sinuosity determine water and sediment dynamics, affecting landscape evolution and connectivity between ecosystems and freshwater species. However, a high-resolution global dataset for the boundaries and geometry of basins is still missing. Using a 90 m resolution digital elevation model, we measured the areas, lengths, widths, aspect ratios, slopes, and elevations of basins over 50 km2 globally. Additionally, we calculated the lengths and sinuosities of the longest river channels within these 0.67 million basins. We built a new global dataset, Basin90m, to present the basins and rivers, as well as their morphological metrics. To highlight the use cases of Basin90m, we explored the correlations among morphological metrics, such as Hack's law. By comparing with HydroSHEDS, HydroATLAS, and Google Earth images, we demonstrated the high accuracy of Basin90m. Basin90m, available in shapefile format, can be used on various GIS platforms, including QGIS, ArcGIS, and GeoPandas. Basin90m has substantial application prospects in geomorphology, hydrology, and ecology. Basin90m is available at https://doi.org/10.5880/GFZ.4.6.2023.004 (He et al., 2023).

Description: Drainage divides separate Earth’s surface into individual river basins. Divide migration impacts the evolution of landforms, regional climate, ecosystems and biodiversity. In this Review, we assess the processes and dynamics of divide migration and offer insights into the impact on climate and biodiversity. Drainage divides are not static: they can move through the processes of gradual migration that is continuous in unsteady landscapes, or sudden through infrequent river capture events. Divides tend to move in the direction of slower erosion, faster uplift or with horizontal tectonic advection, with rates typically ranging between 0.001 and 10 mm year−1, and a global average of 0.6 mm year−1. Evidence of river capture, such as a sharp change in flow direction with an upstream waterfall, can constrain divide migration history. Topographic metrics, such as cross-divide steepness, can predict the migration of drainage divides towards directions with a lower topographic steepness. Divide migration influences the spatial distribution of regional precipitation, temperature and topographic connectivity between species, thereby affecting biodiversity. For example, freshwater fish can migrate into a new drainage basin through river capture, potentially increasing the species richness. Future research should couple advanced landscape evolution models and observations from field and remote sensing to better investigate divide migration dynamics.